The present invention relates to a power actuated fastening tool for driving a fastener, such as a nail, into a substrate, such as a concrete or steel structure.
Power actuated tools for driving a fastener into a substrate conventionally comprise a barrel from which the fastener is expelled by means of a piston driven by detonation of an explosive charge. The barrel is mounted for axial movement within a receiver assembly or body of the tool and after firing can be moved forwardly of the receiver assembly in order to reset the piston into the rear end of the barrel, the barrel with the piston then being retracted back into the body assembly in preparation for the next detonation. For this purpose the barrel normally has an axial slot into which can extend a pawl which engages and restrains the piston when the barrel is moved forwardly so that the piston is reset in the rear end of the barrel during this movement.
In one previously proposed tool of this type as disclosed in International patent application PCT/AU90/00019 the barrel comprises separate front and rear sections, the rear section being telescopically mounted within the front section to permit limited axial movement between the two sections. The construction of the barrel in two separate sections facilitates manufacture of the barrel and the provision for limited axial movement between the front and rear sections enables recoil on firing of the tool to be absorbed by relative axial movement between the two sections to an extended configuration. In this previously proposed tool the two sections of the barrel are held in assembled relationship by retaining segments held by means of a spring clip. In a tool of this type, it is necessary to periodically disassemble the barrel for cleaning purposes, which requires removal of the clip and segments. The disassembly and subsequent reassembly requires a degree of dexterity which is not always possible within the environment of a construction site, and sometimes the segments are dropped and become lost.